In an ignition system for an internal-combustion engine such as an automobile engine, an insulated-gate bipolar transistor (hereinafter referred to as IGBT) is used as a power semiconductor device that drives an inductive load (coils of a transformer).
In the internal-combustion ignition system, an abnormal, high-voltage surge within an automobile battery, if any, causes a power loss, thus resulting in the destruction of the IGBT. The automobile battery is connected to an output (collector) terminal of the IGBT via the inductive load (coils of the transformer). In view of this, a semiconductor circuit that detects a collector voltage (equivalent to a battery voltage) of the IGBT is used to stop the operation of the IGBT during the abnormal voltage in order to avoid the destruction of the IGBT.
Referring to the detection of the collector (output) voltage of the IGBT, Patent Document 1 discloses a semiconductor device that includes an IGBT and thyristor disposed in the same semiconductor substrate.